Repetitive Transcranial Magnetic Stimulation (rTMS) shows the potential to modulate local brain activity, thus resulting in a modulatory action on neurocircuitries implicated in the pathophysiology of Gambling Disorder (GD). We report the case of a GD patient treated with two weeks of high frequency (15 Hz) rTMS over the dorsolateral prefrontal cortex (DLPFC). At baseline and after rTMS treatment the patient underwent a SPECT examination with (123)I-FP-CIT tracer, to test changes in dopamine transporter (DAT) availability. The patient was followed up for six months, to explore safety and clinical correlates of a weekly high frequency rTMS maintenance treatment. Over the six-month follow-up the patient reported no episodes of gambling relapse. Also, the patient did not report craving for gambling or gambling-related symptoms. After two weeks of left DLPFC-rTMS treatment, we found a decrease in DAT availability in striatal regions, that represents a putative neurobiological substrate of dopaminergic pathways modulation. This study suggests that high frequency DLPFC-rTMS deserves further investigations in larger samples, using controlled study designs, to assess its real potential as a treatment for GD.